Scientists genetically engineered rats so that injured neurons in the motor cortex expressed receptors for a growth factor called brain-derived neurotrophic factor (BDNF). The injured neurons recognized the growth factor in the injured area, and then “grew” or regenerated.

But will the regrown nerves actually allow movement?

The researchers will have to test for this at a spinal cord injury site, to see if neurons will send the receptor down the axon and into the spinal cord. If voluntary movement can be restored in larger animals first, the procedure could move on to human clinical trials, offering hope that people paralyzed by spinal cord injuries might someday be able to move again.